The invention is based on a priority application EP 06022701.4 which is hereby incorporated by reference.
The invention relates to a method for distribution of data packets in a single frequency mobile communication network, an access network node base station, and a single frequency mobile communication network.
A so-called single frequency network (SFN) is a broadcast or multicast network, in which several transmitters like e.g. base stations simultaneously send the same signal over the same frequency channel. Thus, for SFN operation, it has to be ensured that all base stations that are involved in SFN transmission transmit at the same time exactly the same data, like e.g. MBMS service data (MBMS=multimedia broadcast multicast service), in exactly the same protocol data unit (PDU) using exactly the same physical radio resource blocks (PRBs).
In UMTS (UMTS=Universal Mobile Telecommunication System), a solution for the transmission of MBMS service data is based on a two node approach in the radio access network (RAN), i.e. a radio network controller (RNC) is responsible for generating transport blocks and for the distribution of the transport blocks to so-called NodeBs via a so-called Iub interface. The time synchronization is realized between the RNC and all NodeBs by transmitting the MBMS service data based on the so-called Connection Frame Number (CFN).
For the Long Term Evolution (LTE) of the 3GPP radio technology (3GPP=Third Generation Partnership Project) as the potential follower of UMTS, a two node architecture consisting of an access network node, as e.g. an access gateway, and a so-called enhanced NodeB as base station has been decided by the Third Generation Partnership Project. The access network node is belonging to the core network, while the enhanced NodeB is located in the radio access network.
For the distribution of MBMS services like e.g. mobile TV, the data have to be distributed from the access network node to several enhanced NodeBs. MBMS services will operate in a Single Frequency Network mode, therefore it has to be ensured that enhanced NodeBs that are involved in SFN transmission for a certain service, transmit within the synchronized radio frames exactly the same data on exactly the same physical layer resources, like e.g. frequencies.
In addition, the access network node as core network element should be radio agnostic, i.e. radio frames and physical layer resources should not be defined by the access network node.
As an LTE system will work for unicast services without a radio network controller, the same concept should be applied for multicast or broadcast services, like the SFN transmission of MBMS service data, as well.
As the access network node should be radio agnostic, the synchronisation procedure should not use radio related parameters.
Further details of the basic principles of content synchronization in LTE systems can be found in the document 3GPP TSGRAN WG 3 Meeting #53bis, Seoul, Korea, 10-13 October 2006, tdoc R3-061534, Architecture for Content Synchronization.